Removal of chlorinated compounds from distillates



R. M. LOVE Dec. 3o, 195s` REMOVAL OF CHLORINATD COMPOUNDS FROM DISTILLATES Fil oct. 6, 1955 REMOVAL OF CHLORNATED COMEOUNDS FROM DISHLLATES Robert M. iLove, Baytown, rlex., assigner, by mesne asslgnments, to Esso Research and Engineering Company, Elizabeth, N. J., a corporation of Deiaware Application October 6, 1955, Serial No. 538,971 d Clainis. (Cl. 208-88) l The present invention is directed to a method for removing chlorinated compounds from hydrocarbon distillates. More particularly, the invention is concerned with treating chlorinated hypochlorite treated hydrocarbon distillates. in its more specific aspects, the invention is directed to removing chlorinated compounds from hylpochlorite treated distillates in a high temperature contreated distillate which contains acidic chlorinated compounds is contacted with a platinum reforming catalyst on an alumina support under naphthenes conversion conditions in the presence of hydrogen whereby the napllthenes are converted and the acidic chlorinated compounds are substantially removed from the treated distillate. Thereafter, gaseous products are separated from the normally liquid products -and a sweetened and reformed fraction substantially free of acidic chlorinated compounds is recovered.

The hydrocarbon feed stock to the presentinvention is suitably a petroleum distillate boiling in the range from about 150 to 450 F. which contains naphthenes and parattins and which may contain some aromatics. This fraction may contain hydrogen sulfide, mercaptans, other sulfur-containing compounds and other acidic materials. Suitably the hydrocarbon distillate may be obtained by distillation of crude petroleums, for example, naphthenebase crude petroleums, such as those found in the Coastal fields of Texas or the California fields.` Other naphthenic fractions which may be produced in some conversion operations may suitably form the feed stock of the present invention.

The hypochlorite solution employed in the practice of the present invention is preferably sodium hypochlorite but may be an alkaline earth hypochlorite such as calv,

cium hypochlorite. It is contemplated that the other alkali metal hypochlorites may be employed, such as lithium and potassium hypochlorites, or that the hypochlorite solution may be a solution of an alkaline earth hypochlorite-such as magnesium, calcium, and strontium hypochlorite.

The hypochlorite solution will ordinarily have an available chlorine content in the range from about 2 grams per liter to about 150 grams per liter; concentrations of about 10 grams per liter gives good results.

The hypochlorite solution when it is a sodium hypoc hlorite solution will preferably have an average sodium hydroxide content ranging from about 5 to about 750 grams of sodium hydroxide per liter. Ordinarily, the

hypochlorite solution employed will contain free sodium hydroxide in the range from about 50 to 100 grams per liter. It may be stated, however, that the present invention has most applicability to treatment of naphthas which have been contacted with hypochlorite solutions having a low level of causticity since naphthas treated with sodium hypochlorite having a small amount of free sodium hydroxide are generally more unstable than those having a high level of free sodium hydroxide.

. In practicing the present invention, it may be desirable to remove hydrogen sulde and/or other acidic materials reactive with the hypochlorite solution and this may suitably be accomplished by contacting the naphthenic hy-l drocarbon distillate with an aqueous alkaline solution, such as an aqueous alkali metal hydroxide solution, for example, sodium hydroxide. Suitably, the sodium hydroxide solution may have a Baume gravity ranging from 5 to about 15. Hydrogen sulfide may be removed employing a 5 Baum sodium hydroxide solution. Other acidic material, such as phenolic bodies and the like, may be extracted with a stronger aqueous sodium hydroxide solution, such as one having a Baum gravity of about The latter strength solution is suitable to extract a portion of the mercaptans, such as those of the lower molecular weight, such as methyl, ethyl, propyl and butyl mercaptans and anyaromatic mercaptans which may be present. Some of the pentyl and hexyl mercaptans may also be removed with the stronger alkaline solution. It is desirable to remove such mercaptans since consumption of chlorine in the subsequent hypochlorite step is thereby reduced.

The hypochlorite treating step of the present invention may suitably be conducted at temperatures in the range from 60 up to about 120 F. with temperatures within the range from about to about 100 F. being preferred. Under some conditions, temperatures up to about 250 F. may be used but when the higher temperatures are employed, sufhcient pressure should be superimposed to maintain the components in the liquid phase.

In the reforming or conversion operation, temperatures may suitably range from about 900 to about 1000 F. with desirable results being obtained at about 950 F.

After a period of time the reforming catalystmay become fouled with carbonaceous and other deposits and it may be desirable to burn these materials from the catalyst. These combustion operations are suitably termed regeneration operations and may be conducted at a tem perature from 1050 to 1100 F. in a combustion operation in which non-volatile carbonaceous deposits and carbon are removed from the catalyst by burning in the presence of free oxygen,

The pressures employed in the conversion operation preferably range from 200 to 400 pounds per square inch gauge but pressures as low as 50 pounds per square inch gauge and as high as 700 pounds per square inch gauge may be used.

The amount of hydrogen employed may range from about 1000 cubic feet to about 10,000 cubic feet per `barrel of hydrocarbon feed. The preferred operation will employ about 5000 cubic feet of hydrogen per barrel of feed. While pure hydrogen may be used ordinarily, it is preferred to employ a free hydrogen-containing gas, such as a make gas, in the operation. y

The platinum reforming catalyst employed in the present invention will suitably be -a platinum catalyst supported on alumina containing from about 0.1% to about 3.0% by weight of platinum, preferably from 0.2% to 1.0% by weight. The alumina on which the platinum is deposited is a purified alumina, such as gamma alumina derived from boehmite. Although gamma or purified 'alumina is preferred, platinum on puriiied alumina' derived from other sources may suitably be used. lt is to be emphasized that the alumina preferably should be free from silica and other undesirable impurities.

In accordance with the present invention, a surprising and unusual result is obtained in that the undesirable acidic chlorinated compounds in the hypochlorite treated hydrocarbon `distillate are charged to a platinum reforming catalyst in the presence of hydrogen to remove the acidic chlorinated compounds. Besides removing the acidic chlorinated compounds, the platinum reforming operation is improved by the presence of the acidic chlorinated compounds and the naphthenes are converted to aromatics and the acidic chlorinated compounds are substantially removed such that there is recovered from the reforming operation a sweetened and reformed product free of chlorinated compounds. Not only does the sweetening or treatment of the naphthenes-containing fraction with hypochlorite result in the removal of acidic sulfur compounds to make the subsequent treating operation beneficial, but the removal of the sulfur compounds in substantial amounts by the hypochlorite treat is beneficial in the platinum reforming operation in that it is undesirable tohave substantial amounts of sulfur present in the platinum reforming of naphthenes.

The present invention -will be further illustrated by reference to the drawing `in which the single ligure is a ow diagram of a preferred mode.

Referring now to the drawing, a sour naphthenic hydrocarbon of the type mentioned supra is introduced into the system through line 11 controlled by valve 12 which discharges into an incorporator or other mixing device 13. Mixing device 13 is shown as -a bathe-plate incorporator. Introduced `into line 11 by way of line 14 controlled by valves 15 and 16 is an aqueous alkaline solution of the type mentioned. This solution contacts the sour naphthenic hydrocarbon in line 11 and in the incorporator 13 and results in the removal of some mercaptans and acidic bodies. The -admixture passes from the incorporator 13 by line 17 into a caustic settling zone 18 wherein a separation is made by gravity between the naphthenic hydrocarbon and the caustic solution. The caustic solution is separated and withdrawn by line 19 controlled by valve 20 and all or part of the withdrawn Solution may be recycled by way of branch line 21 containing pump 22 and valve 23 to line 14 for recycling through incorporator 13 in admixture with the sour naphthenic hydrocarbons. It is to be understood that the caustic treat or wash may be applied in stages with a weak caustic treat in one stage and a stronger caustic treat in another stage. For example, a preliminary treat of 5 Baum may be used in a first stage and a second treat of 15 Baum caustic may be used in a second stage. In any event, the caustic treated naphthenic hydrocarbon is removed from zone 18 by line 24 wherein it is admixed with an aqueous alkaline hypochlorite solution, such as sodium hypochlorite, introduced into line 24 by way of line 25 from a source which will be described more fully hereinafter. The naphthenic hydrocarbons and hypochlorite solution then pass into an incorporator or mixing device 26 which is similar to mixing device 13 and after intimate contact therein is discharged by way of line 27 into a hypochlorite settling zone 28 which is of suicient size and capacity to allow separation of the used hypochlorite solution from the hypochlorite treated naphthenic hydrocarbon. The used hypochlorite solution is withdrawn from zone 28 by line 29 and preferably is recycled by line 30 to the hypochlorite preparation zone 31. The hypochlorite preparation zone 31 has chlorine added to it by line 32 controlled by valve 33 to restore the activity of the used hypochlorite solution for use in the process as has been described, the hypochlorite being withdrawn from zone 31 by line 25. yIt may be necessary to add sodium hydroxide to the used hypochlorite solution and this may suitably be done by introducing fresh sodium hydroxide by line 34 controlled by valve 35. The used hypochlorite solution may be discarded as desired by opening valve 36 in line 29.

The hypochlorite treated hydrocarbon contains, as a result of the hypochlorite treatment, acidic chlorinated compounds of the type, such as sulfonyl, sulfenyl, and sulnyl chlorides. These compounds are deleterious in motor fuel in that they deleteriously affect the product quality of the finished motor fuel, such as breakdown or induction period (ASTM S25-46). In accordance with the present invention the acidic chlorinated compounds are converted or substantially removed and the naphtlienes are converted to aromatic lhydrocarbons which result in the appreciation of the octane number of the reformed product. To this end, the hypochlorite treated naplithenic hydrocarbon discharges by line 37 into a furnace 38 containing a heating coil 39 to which heat is supplied by gas burners 40. Admixed with the hypochlorite treated naphthenic hydrocarbon in line 37 prior to introduction into coil 39 is a hydrogen-containing gas introduced by line 41 from a source which Will be described in more detail hereinafter. In coil 39 the hydrocarbon is vaporized and heated to a naphthene conversion temperature and thereafter the mixture of hydrogen and heated vaporized hydrocarbon feed is discharged by line 42 to a platinum reforming zone 43 which suitably may comprise a plurality of beds of platinum reforming catalyst supported on alumina as has been described. In platinum reforming zone 43, which is maintained at suitable conditions of temperature and pressure, the naphthones are converted to aromatics and the acidic chlorinated compounds are converted to hydrogen chloride and hydrogen sulfide. The acidic chlorinated compounds exert a beneficial effect in reforming zone 43 and provide for enhancing the octane number of the converted product. The converted product including aromatics and the hydrogen sulfide and hydrogen chloride are removed from zone 43 by line 44, and are passed through cooling zone 45 and thence by line 46 into a separation zonel47 wherein the gaseous products are separated from the liquid products. The gaseous products contain hydrogen and hydrogen sulfide and may be Withdrawn from zone 47 by line 48 and recycled to line 37 by line 41. In view of the presence of hydrogen sulfide in small amounts in the make gas, it may be desirable to bypass all or part of the gas in line 41 into a caustic scrubber 49 which connects to line 41 by line 50 controlled by valve 51 and line 52 contro-lied by valve 53. The make gas may pass through line 50 into scrubber 49 wherein it contacts a caustic solution of sufficient strength which may range from 2 to 15 Baum introduced by line 54 controlled by valve 55 wherein the caustic solution and the gas contact each other concurrently in a scrubber 49. The used caustic solution may he discharged from scrubber 49 by line 56 and recycled to line 54 by line 57 containing pump 58 and all or part of the caustic solution may be discarded from line 56 by opening valve 59.

It may be desirable since hydrogen is produced in the process to discard part of the make gas and this may be accomplished by opening valve 60 in line 41.

Some water is formed in the process and the hydrogen chloride is largely dissolved in the water and this water is withdrawn from separator 47 by line 61 while the sweetened and reformed product is recovered by line 62. lt may be desirable to treat further the sweetened and reformed product, which is substantially free of acidic chlorinated compounds of the type mentioned supra, by giving the product in line 62 a caustic Wash and then subiecting it to other treatment such as solvent extraction, fractional distillation and the like for separation and recovery of the desired aromatics.

Since the platinum catalyst in reforming zone 43 may become fouled with carbonaceous deposits, it may be desirable to burn off these carbonaceous deposits after a period of time which may range from about to about 500 hours. This suitably may be accomplished by introducing a free oxygen-containing gas into contact with the platinum reforming catalyst. Provision is made for burning off the carbonaceous deposits by introducing a ue gas or other inert gas by line 63 controlled by valve 64 into a furnace 65 provided with a coil 66 and heated by gas burner 67. The heated flue gas containing the required amount of oxygen is Withdrawn from furnace 65 by line 66a and discharged into line 68 into the platinum reforming zone 43 in contact with the catalyst containing non-volatile carbonaceous material. The combustion gases are withdrawn from zone 43 by line 69 and may be discharged, all or in part, from the system by line 70 controlled by valve 71. Preferably a portion of the ue gas is recycled by throttling valve 72. Air is introduced into line 63 through line 73 controlled by valve 74.

It may be desirable to adjust the temperature of the free oxygen-containing gas and to this end furnace 65 may be bypassed, with a portion of the ue gas, by opening valve 75 in line 69. v

It is desirable to control the hypochlorite sweetening operation to provide an amount of chlorine on the platinum reforming catalyst in the range between 0.5% to 0.6% by weight. This is accomplished by sweetening the sour naphthenic hydrocarbon to provide an amount of the chlorides of the sulfenyl, sulfenyl and sulnyl chlorides type in the range between about 2 and about 60 parts per million of the hypochlorite treated stock charged to the reforming zone 43. Preferably the content of the sulfonyl, sulfenyl and sulnyl chlorides in the hypochlorite treated stock is in the range between about 2 to about 15 n parts per million. It may be necessary to adjust the amount of chlorides in the feed to the reforming zone 43 and this may suitably be done, if necessary, by charging into the reforming zone 43 a feed stock which is free of the several chlorides of the type mentioned before or has a lower content thereof. For example, a naphthenic hydrocarbon fraction which does not require sweetening may be charged together with the hypochlorite sweetening stock.

The reforming zone 43 besides removing the objectionable chlorinated compounds by converting same also serves to reduce further the sulfur content of the hypochlorite treated stock by destroying or converting the several chlorides mentioned supra to hydrogen chloride and HZS, which may be removed by subsequent treatment as has been described.

It will be seen from the foregoing description taken with the drawing that a new and improved process has been provided. The compounds which are objectional in hypochlorite sweetened oil are benecial in the re- (i forming operation which removes the objectional cornpounds from the hypochlorite sweetened oil. This is indeed useful in that motor fuels and aromatic and/or parainic solvents of enhanced quality may be obtained in accordance with the present invention.

The nature and objects of the present invention having been completely described and illustrated, what I wish to claim as new and useful and to secure by Letters Patent is:

l. A method for treating a sour hydrocarbon distillate boiling in the gasoline range and containing naphthenes which comprises treating said distillate with an aqueous sodium hypochlorite solution containing from about 5 to about 750 grams of sodium hydroxide per liter and having an available chlorine content in the range from about 2 to about 150 grams per liter whereby acidic chlorinated compounds selected from the group consisting of the sulfonyl, sulfenyl, and sullinyl chlorides in an amount in the range from about 2 to about 60 parts per million are formed, separating said treated distillate from said hypochlorite solution, and then contacting the treated distillate with an alumina supported platinum reforming catalyst to provide an amount of chlorine on the catalyst in the range between 0.5 and 0.6 percent by weight under naphthenes conversion conditions at a temperature in the range from about 900 to about l000 F. whereby said naphthenes are converted and said acidic chlorinated compounds are substantially removed from the treated distillate.

2. A method in accordance with claim 1 in which the t hypochlorite solution contains from about 50 to about grams of sodium hydroxide per liter and has an available chlorine content of about 10 grams per liter.

3. A method in accordance with claim l in which the hydrocarbon distillate boils in the range from about to about 450 F.

4. A method in accordance with claim l in which the hydrocarbon distillate contains paraflins and in which parailins and aromatics are recovered from the converted treated distillate.

References Cited in the lile of this patent UNITED STATES PATENTS 2,626,893 Morrow Jan. 27, 1953 2,642,384 Cox June 16, 1953 2,717,230 Murray et al. Sept. 6, 1955 2,721,166 Earhart Oct. 18, 1955 2,758,064 Haensel Aug. 7, 1956 

1. A METHOD FOR TREATING A SOUR HYDROCARBON DISTILLATE BOILING IN THE GASOLINE RANGE AND CONTAINING NAPHTHENES WHICH COMPRISES TREATING SAID DISTILLATE WITH AN AQUEOUS SODIUM HYPOCHLORITE SOLUTION CONTAINING FROM ABOUT 5 TO ABOUT 750 GRAMS OF SODIUM HYDROXIDE PER LITER AND HAVING AN AVAILABLE CHLORINE CONTENT IN THE RANGE FROM ABOUT 2 TO ABOUT 150 GRAMS PER LITER WHEREBY ACIDIC CHLORINATED COMPOUNDS SELECTED FROM THE GROUP CONSISTING OF THE SULFONYL, SULFENYL, AND SULFINYL CHLORIDES IN AN AMOUNT IN THE RANGE FROM ABOUT 2 TO ABOUT 60 PARTS PER MILLION ARE FORMED, SEPARATING SAID TREATED DISTILLATE FROM SAID HYPOCHLORITE SOLUTION, AND THEN CONTACTING THE TREATED DISTILLATE WITH AN ALUMINA SUPPORTED PLATINUM REFORMING CATALYST TO PROVIDE AN AMOUNT OF CHLORINE ON THE CATALYST IN THE RANGE BETWEEN 0.5 TO 0.6 PERCENT BY WEIGHT UNDER NAPHTHENES CONVERSION CONDITIONS AT A TEMPERATURE IN THE RANGE FROM ABOUT 900* TO ABOUT 1000*F. WHEREBY SAID NAPHTHENES ARE CONVERTED AND SAID ACIDIC CHLORINATED COMPOUNDS ARE SUBSTANTIALLY REMOVED FROM THE TREATED DISTILLATE. 